Floating storage tank



Oct. 20, 1953 l. w. ALCORN FLOATING STORAGE TANK Filed Jan. 5, 1949 Illllll lllllllll mnmm:

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JNVENTOR. IRWIN W. AL CORN A TTORNE Y Patented Oct. 20, 1953 FLOATING STORAGE TAN K Irwin W. Alcorn,

Pure Oil Company, of Ohio Houston, Tex., assignor to The Chicago, 111., a corporation Application January 5, 1949, Serial No. 69,346 4 2 Claims. (Cl. 114.5,)

This invention relates to improvements in containers, such as storage tanks, and is particularly useful as here shown embodied in a storage tank for holding and storing liquids while floating in water.

The underwater drilling of oil wells creates not only many problems involved in the actual sinking of the well, but also the problem of storing such oil as is obtained from the well until the oil is ready to betransported to a point ashore. Common practice has been to run the oil into an ordinary tanker which is moored adjacent to the well, but this procedure has several disadvantages, principal among which is the fact that the ordinary tanker represents a very heavy investment which is too much to be kept at a site merely for the storage of oil. A second disadvantage which is technological in nature i that the tanker, for maximum stability in the oil drilling and storing operation, must be kept headed into the wind in order to make possible safest operation.

Accordingly, it is a fundamental object of the invention to provide a tank for use in the storing of oil near submerged oil wells, which tank is buoyant so that it will float and stable so that it can be moored at a fixed position and not require alteration in its direction to keep it headed into the wind.

The second object of the invention is to provide a storage tank having inlets and outlets so that its buoyancy will be adjustable to make it possible to submerge the tank entirely to provide for underwater storage of oil.

Other objects and advantages of the invention will in part be obvious and in part appear hereinafter.

The invention, accordingly, comprises a container which is a surface of revolution defined by rotating a continuous curve about a vertical axis to generate a solid symmetrical about the vertical axis but asymmetrical with respect to a substantially central horizontal plane, sothat a solid of revolution is generated in which the upper and lower halves are of similar though different conflgurations and volumes. More specifically, the surface may be considered as being formed of an ellipsoid generated by rotation of an ellipse about its minor axis having the lower section foreshortened along the minor axis so that the bottom section of the solid presents a flat effect and the top section essentially truly ellipsoidal or slightly lengthened along the minor axis to give it a heightened effect.

A more detailed understanding of the inven- .2 tion can be had by reference to the accompanying drawings illustrating a preferred embodiment of the tank in which:

Figure l represents'a plan view of the storage tank; and l 1 Figure 2 represents a, view partially in section to illustrate the interior structure thereof.

Referring now to the drawings, in particular Figure 2, It represents a shell forming the body of a storage tank which is divided horizontally at a level corresponding substantially to what would be the major axis of a true ellipsoid by a bulkhead l l and which is also further subdivided into compartments by bulkheads, such as l2. and 2. By this arrangement of horizontal and transverse bulkheads, the tank is subdivided into a number of compartments in the upper and lower sections of the tank, which compartments can be arranged to communicate with each other. A central support 13 maintains or provides-adequate strength in the center of the tankwhere the spread between the top and bottom is greatest. Provision is made for loading the tank with oil by way of intake or discharge pipes l4 and it which communicate separately with the upper and lower sections of the tank, respectively. In corresponding fashion, vents l6 and l! are provided to vent the compartments as they are filled with products. On the exterior of the tank, there is provided a stairway or catwalk l8 to permit easy access to the various parts of the top surface thereof, in particular, the exits from the vents and intake pipes. Likewise, on the exterior surface of the tank, there are provided a plurality of mooring lugs l9 and 20, to permit mooring the tank to a specific location in a body of water.

Though the tank has a vertical axi of symmetry and in the plan projection it has an outer circumference which is circular, thus indicating it to be a surface of revolution, it is not symmetrical about a horizontal axis or plane, for it is highly desirable that it not be a perfectly symmetrical geometric figure in order to develop the greatest degree of stability thereof. Thus, the bulkhead ll, shown in Figure 2, which divides the tank transversely into an upper and lower section is drawn at a level which would correspond substantially to the major axis of an ellipse were the vertical section of the tank to be a true ellipse. The preferred form is such that the upper section of the tank is essentially ellipsoidal and the lower section is ellipsoidal but has the minor axis fores'hortened so that the ratio thereof to the full minor axis is about 0.6 to 0.95. The combination of the two sections of the tank is made so that the outer surface of the tank represents an essentially continuous curve which blends from an ellipse in the upper portion into practically a straight line near the extremity of the lower portion of the minor axis.

In section, it will be seen, therefore, that the shape of the tank is such that the tank when floating in water will have its center of gravity low at all time's and will'have its'center of buoyancy relatively high at all times, thereby tending to maintain the tank under conditions of maximum stability while it is afloat. Also, any face of the tank presents a rounded face to'the'rolling of waves so that the tank is disturbed only to a minimum degree by rollingof wavesincontrast to tankers which, when moored "at a given place to collect oil, can be struck broadside by waves and made to roll severely.

In use, the tank is equipped with valves to permit interconnection or intercommunic'ation between the compartments in the upper half or between the compartments in the lower half of the tank. For greatest stability'in use, the tank is first set in place and the lower half filled with water to cause the tank to take up a floating position of great stability in the water. When the upper section of the tank is filled with oil, additional oil can beadded to the lower portion of the tank to displace all or only part of the water therein. In this manner, a great degree of stability can be maintained during the entire period of use of the tank.

Though the invention has been described with only a single embodiment and has been described particularly with reference to the collection of oil being obtained from underwater wells, it is apparent that the tank is also useful for storing oil in or under water. Thus, the illustration is not to be considered as limiting the invention, but merely as illustrative of the spirit and scope thereof.

4 What is claimed is: 1. A submersible floating storage tank for liquids, comprising a tank the surface of which" is essentially a surface of revolution, said surface being a continuous curve generated by rotating about its minor axis an ellipse truncated adjacent one end of its minoraxis and perpendicular thereto, the truncated portion of said elli'pse generating the bottom of the tank, said tank being divided horizontally into an upper and lower section by a horizontal bulkhead located substan- IRWIN W. ALCORN.

References Cited 'in the file of this patent UNITED STATES PATENTS Number Name A Date V 195,954 Rowland Oct, 9, 1877 1,622,787 Horton Mar. 29,1927 2,297,002 Larson Sept. 29, 1942 2,314,555 Preuss Mar. 23, 1943 2,341,547 Heineman Feb. l5, 1944 2,402,790 Vbrenkamp June 25, 1946 2,417,337 Whitesell Mar. 11, 19 47 2,457,118 Boardnian Dec. 28, I948 2,562,602 Caquot July 31, I] 

